Buggy code:
public class ModClusterExtension implements XMLStreamConstants , Extension { public static final String SUBSYSTEM_NAME = "modcluster" ; private static final PathElement sslConfigurationPath = PathElement . pathElement ( SSL , CONFIGURATION ) ; private static final PathElement configurationPath = PathElement . pathElement ( MOD_CLUSTER_CONFIG ) ; @ Override public void initialize ( ExtensionContext context ) { EnumSet < Flag > runtimeOnly = EnumSet . of ( RUNTIME_ONLY ) ; ModClusterLogger . ROOT_LOGGER . debugf ( "Activating<seq2seq4repair_space>Mod_cluster<seq2seq4repair_space>Extension" ) ; final SubsystemRegistration subsystem = context . registerSubsystem ( ModClusterExtension . SUBSYSTEM_NAME , CURRENT . getMajorVersion ( ) , CURRENT . getMinorVersion ( ) ) ; final ManagementResourceRegistration registration = subsystem . registerSubsystemModel ( SUBSYSTEM ) ; registration . registerOperationHandler ( ADD , INSTANCE , INSTANCE , false ) ; registration . registerOperationHandler ( REMOVE , ModClusterSubsystemRemove . INSTANCE , ModClusterSubsystemRemove . INSTANCE , false ) ; registration . registerOperationHandler ( DESCRIBE , ModClusterSubsystemDescribe . INSTANCE , ModClusterSubsystemDescribe . INSTANCE , false , PRIVATE ) ; if ( context . isRuntimeOnlyRegistrationValid ( ) ) { registration . registerOperationHandler ( "list-proxies" , ModClusterListProxies . INSTANCE , ModClusterListProxies . INSTANCE , false , runtimeOnly ) ; registration . registerOperationHandler ( "read-proxies-info" , ModClusterGetProxyInfo . INSTANCE , ModClusterGetProxyInfo . INSTANCE , false , runtimeOnly ) ; registration . registerOperationHandler ( "read-proxies-configuration" , ModClusterGetProxyConfiguration . INSTANCE , ModClusterGetProxyConfiguration . INSTANCE , false , runtimeOnly ) ; registration . registerOperationHandler ( "add-proxy" , ModClusterAddProxy . INSTANCE , ModClusterAddProxy . INSTANCE , false ) ; registration . registerOperationHandler ( "remove-proxy" , ModClusterRemoveProxy . INSTANCE , ModClusterRemoveProxy . INSTANCE , false ) ; registration . registerOperationHandler ( "refresh" , ModClusterRefresh . INSTANCE , ModClusterRefresh . INSTANCE , false , runtimeOnly ) ; registration . registerOperationHandler ( "reset" , ModClusterReset . INSTANCE , ModClusterReset . INSTANCE , false , runtimeOnly ) ; registration . registerOperationHandler ( "enable" , ModClusterEnable . INSTANCE , ModClusterEnable . INSTANCE , false ) ; registration . registerOperationHandler ( "disable" , ModClusterDisable . INSTANCE , ModClusterDisable . INSTANCE , false ) ; registration . registerOperationHandler ( "stop" , ModClusterStop . INSTANCE , ModClusterStop . INSTANCE , false ) ; registration . registerOperationHandler ( "enable-context" , ModClusterEnableContext . INSTANCE , ModClusterEnableContext . INSTANCE , false ) ; registration . registerOperationHandler ( "disable-context" , ModClusterDisableContext . INSTANCE , ModClusterDisableContext . INSTANCE , false ) ; registration . registerOperationHandler ( "stop-context" , ModClusterStopContext . INSTANCE , ModClusterStopContext . INSTANCE , false ) ; } final ManagementResourceRegistration configuration = registration . registerSubModel ( ModClusterExtension . configurationPath , ModClusterSubsystemDescriptionProviders . CONFIGURATION ) ; final ManagementResourceRegistration ssl = configuration . registerSubModel ( ModClusterExtension . sslConfigurationPath , ModClusterSubsystemDescriptionProviders . SSL ) ; configuration . registerReadWriteAttribute ( ADVERTISE_SOCKET , null , new WriteAttributeHandlers . StringLengthValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( PROXY_LIST , null , new WriteAttributeHandlers . StringLengthValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( PROXY_URL , null , new WriteAttributeHandlers . StringLengthValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( ADVERTISE , null , new WriteAttributeHandlers . ModelTypeValidatingHandler ( ModelType . BOOLEAN , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( ADVERTISE_SECURITY_KEY , null , new WriteAttributeHandlers . StringLengthValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; <START_BUG> configuration . registerReadWriteAttribute ( EXCLUDED_CONTEXTS , null , new WriteAttributeHandlers . ModelTypeValidatingHandler ( ModelType . BOOLEAN , true ) , Storage . CONFIGURATION ) ; <END_BUG> configuration . registerReadWriteAttribute ( AUTO_ENABLE_CONTEXTS , null , new WriteAttributeHandlers . ModelTypeValidatingHandler ( ModelType . BOOLEAN , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( STOP_CONTEXT_TIMEOUT , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( SOCKET_TIMEOUT , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( STICKY_SESSION , null , new WriteAttributeHandlers . ModelTypeValidatingHandler ( ModelType . BOOLEAN , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( STICKY_SESSION_REMOVE , null , new WriteAttributeHandlers . ModelTypeValidatingHandler ( ModelType . BOOLEAN , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( STICKY_SESSION_FORCE , null , new WriteAttributeHandlers . ModelTypeValidatingHandler ( ModelType . BOOLEAN , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( WORKER_TIMEOUT , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( MAX_ATTEMPTS , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( FLUSH_PACKETS , null , new WriteAttributeHandlers . ModelTypeValidatingHandler ( ModelType . BOOLEAN , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( FLUSH_WAIT , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( PING , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( SMAX , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( TTL , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( NODE_TIMEOUT , null , new WriteAttributeHandlers . IntRangeValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( BALANCER , null , new WriteAttributeHandlers . StringLengthValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( DOMAIN , null , new WriteAttributeHandlers . StringLengthValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( DYNAMIC_LOAD_PROVIDER , null , new ModClusterExtension . WriteDynamicLoadProviderOperationHandler ( ) , Storage . CONFIGURATION ) ; configuration . registerReadWriteAttribute ( SIMPLE_LOAD_PROVIDER , null , new ModClusterExtension . WriteSimpleLoadProviderOperationHandler ( ) , Storage . CONFIGURATION ) ;

Fix:
configuration . registerReadWriteAttribute ( EXCLUDED_CONTEXTS , null , new WriteAttributeHandlers . StringLengthValidatingHandler ( 1 , true ) , Storage . CONFIGURATION ) ;